Cystic fibrosis (CF) is an autosomal genetic disease that affects approximately 30,000 people in the United States and approximately 70,000 people worldwide. Approximately 1,000 new cases of CF are diagnosed each year. Most patients are diagnosed with CF by the age of two, and more than half of the CF population is 18 years in age or older. Despite progress in the treatment of CF, there is no cure.
Cystic fibrosis (CF) is caused by loss-of-function mutations in the CF transmembrane conductance regulator (CFTR) protein, a cAMP-regulated chloride channel expressed primarily at the apical plasma membrane of secretory epithelia in the airways, pancreas, intestine, and other tissues. CFTR is a large, multidomain glycoprotein consisting of two membrane-spanning domains, two nucleotide-binding domains (NBD1 and NBD2) that bind and hydrolyze ATP, and a regulatory (R) domain that gates the channel by phosphorylation. Nearly 2000 mutations in the CFTR gene have been identified that produce the loss-of-function phenotype by impairing its translation, cellular processing, and/or chloride channel gating. The F508del mutation, which is present in at least one allele in ˜90% of CF patients, impairs CFTR folding, stability at the endoplasmic reticulum and plasma membrane, and chloride channel gating (Dalemans et al. 1991; Denning et al. 1992; Lukacs et al. 1993; Du et al. 2005). Other mutations primarily alter channel gating (e.g., G551D), conductance (e.g., R117H), or translation (e.g., G542X) (Welsh and Smith 1993). The fundamental premise of CFTR corrector and potentiator therapy for CF is that correction of the underlying defects in the cellular processing and chloride channel function of CF-causing mutant CFTR alleles will be of clinical benefit. Correctors are principally targeted at F508del cellular misprocessing, whereas potentiators are intended to restore cAMP-dependent chloride channel activity to mutant CFTRs at the cell surface. In contrast to current therapies, such as antibiotics, anti-inflammatory agents, mucolytics, nebulized hypertonic saline, and pancreatic enzyme replacement, which treat CF disease manifestations, correctors and potentiators correct the underlying CFTR anion channel defect.
In view of the above, CFTR correctors of formula (I) are considered to be of value in the treatment and/or prevention of CF and related disorders.